Ecotropic Murine Leukemia Virus Infection of Glial Progenitors Interferes with Oligodendrocyte Differentiation: Implications for Neurovirulence.
3T3 Cells; Animals; Cell Line; Cell Proliferation; Cell Survival; env/biosynthesis; Female; Gene Products; Leukemia Virus; Male; Mice; Motor Neuron Disease/*virology; Murine/*pathogenicity; Neural Stem Cells/*virology; Neurogenesis/*physiology; Neuroglia/*virology; Oligodendroglia/cytology/virology; Retroviridae Infections/*complications; Transgenic
UNLABELLED: Certain murine leukemia viruses (MLVs) are capable of inducing fatal progressive spongiform motor neuron disease in mice that is largely mediated by viral Env glycoprotein expression within central nervous system (CNS) glia. While the etiologic mechanisms and the glial subtypes involved remain unresolved, infection of NG2 glia was recently observed to correlate spatially and temporally with altered neuronal physiology and spongiogenesis. Since one role of NG2 cells is to serve as oligodendrocyte (OL) progenitor cells (OPCs), we examined here whether their infection by neurovirulent (FrCasE) or nonneurovirulent (Fr57E) ecotropic MLVs influenced their viability and/or differentiation. Here, we demonstrate that OPCs, but not OLs, are major CNS targets of both FrCasE and Fr57E. We also show that MLV infection of neural progenitor cells (NPCs) in culture did not affect survival, proliferation, or OPC progenitor marker expression but suppressed certain glial differentiation markers. Assessment of glial differentiation in vivo using transplanted transgenic NPCs showed that, while MLVs did not affect cellular engraftment or survival, they did inhibit OL differentiation, irrespective of MLV neurovirulence. In addition, in chimeric brains, where FrCasE-infected NPC transplants caused neurodegeneration, the transplanted NPCs proliferated. These results suggest that MLV infection is not directly cytotoxic to OPCs but rather acts to interfere with OL differentiation. Since both FrCasE and Fr57E viruses restrict OL differentiation but only FrCasE induces overt neurodegeneration, restriction of OL maturation alone cannot account for neuropathogenesis. Instead neurodegeneration may involve a two-hit scenario where interference with OPC differentiation combined with glial Env-induced neuronal hyperexcitability precipitates disease. IMPORTANCE: A variety of human and animal retroviruses are capable of causing central nervous system (CNS) neurodegeneration manifested as motor and cognitive deficits. These retroviruses infect a variety of CNS cell types; however, the specific role each cell type plays in neuropathogenesis remains to be established. The NG2 glia, whose CNS functions are only now emerging, are a newly appreciated viral target in murine leukemia virus (MLV)-induced neurodegeneration. Since one role of NG2 glia is that of oligodendrocyte progenitor cells (OPCs), we investigated here whether their infection by the neurovirulent MLV FrCasE contributed to neurodegeneration by affecting OPC viability and/or development. Our results show that both neurovirulent and nonneurovirulent MLVs interfere with oligodendrocyte differentiation. Thus, NG2 glial infection could contribute to neurodegeneration by preventing myelin formation and/or repair and by suspending OPCs in a state of persistent susceptibility to excitotoxic insult mediated by neurovirulent virus effects on other glial subtypes.
Li Ying; Dunphy Jaclyn M; Pedraza Carlos E; Lynch Connor R; Cardona Sandra M; Macklin Wendy B; Lynch William P
Journal of virology
2016
2016-01
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1128/JVI.03156-15" target="_blank" rel="noreferrer noopener">10.1128/JVI.03156-15</a>
Changes in BiP (GRP78) levels upon HSV-1 infection are strain dependent.
3T3 Cells; Animals; Carrier Proteins/*biosynthesis/genetics; Heat-Shock Proteins/*biosynthesis/genetics; Herpesvirus 1; Human/isolation & purification/*physiology; Humans; Messenger/metabolism; Mice; Molecular Chaperones/*biosynthesis/genetics; RNA
BiP (grp78) is a chaperone protein which can also regulate the unfolded protein response of the cell. Levels of BiP increased in cells infected by the small plaque producing, cell associated, neuroinvasive strains of HSV-1 (SP7, 490) but decreased in cells infected with KOS, a large plaque, attenuated strain. BiP protein synthesis continued early in infection and BiP was sequestered and its degradation was limited during SP7 infection. BiP protein synthesis stopped and the protein was degraded in KOS infected cells. These viral strain dependent differences in BiP concentration may influence other aspects of the viral interaction with the target cell and its host.
Mao H; Palmer D; Rosenthal K S
Virus research
2001
2001-08
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/s0168-1702(01)00257-x" target="_blank" rel="noreferrer noopener">10.1016/s0168-1702(01)00257-x</a>
Mice transgenic for simian immunodeficiency virus nef are immunologically compromised.
*Genes; *Herpesvirus 1; *Immunocompromised Host; 3T3 Cells; Aging; Animals; Antibodies; Antibody Formation; Cellular; Cercopithecus aethiops; Female; Herpes Simplex/*immunology; HIV/pathogenicity; Human; Humans; Immunity; Immunoglobulin G/blood; Kinetics; Male; Mice; nef; Simian Immunodeficiency Virus/*genetics/pathogenicity; Transgenic; Vero Cells; Viral/biosynthesis/blood
An intact nef gene is essential for rapid development of immunodeficiency in human immunodeficiency virus and simian immunodeficiency virus infections. To assess the role of nef in the immune response, mice transgenic for SIV nef were constructed and the humoral and cellular immune response to herpes simplex virus type-1 (HSV-1), measured. Mice transgenic for SIVmac239 nef exhibited a significantly increased mortality rate when challenged with HSV-1 and also showed unusual antibody kinetics in response to viral challenge. During a 32-week period following exposure to HSV, it was noted that IgG subclass titers continued to rise in the nef+ animals, while titers of nef- animals decreased. Additionally, following secondary challenge with HSV, nef- mice had a significantly greater rise in HSV-neutralizing antibody titers than nef+ mice. A decreased proliferative response to the T cell mitogen, PHA, was noted in the nef+ animals. These results suggest that the presence of nef+ is sufficient to induce immune dysfunction.
Larsen N B; Kestler H W; Docherty J J
Journal of biomedical science
1998
1998-08
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1007/bf02255857" target="_blank" rel="noreferrer noopener">10.1007/bf02255857</a>
Osteoactivin promotes osteoblast adhesion through HSPG and alphavbeta1 integrin.
3T3 Cells; Actin Cytoskeleton/physiology; ADHESION; Alkaline Phosphatase/biosynthesis; Animals; Antibodies/immunology; Cell Adhesion; Cell Differentiation; Cell Line; Cell Proliferation; Chlorates/pharmacology; Extracellular Signal-Regulated MAP Kinases/biosynthesis; Eye Proteins/genetics/immunology/*metabolism; Focal Adhesion Kinase 1/biosynthesis; Focal Adhesions; Heparan Sulfate Proteoglycans/*metabolism; Heparin/pharmacology; Inbred C57BL; INTEGRIN; Membrane Glycoproteins/genetics/immunology/*metabolism; Mice; OSTEOACTIVIN; OSTEOBLAST; OSTEOBLAST DIFFERENTIATION; Osteoblasts/*physiology; Osteogenesis/physiology; Protein Binding; Rats; Receptors; Recombinant Proteins; Vitronectin/immunology/*metabolism
Osteoactivin (OA), also known as glycoprotein nmb (gpnmb) plays an important role in the regulation of osteoblast differentiation and function. OA induced osteoblast differentiation and function in vitro by stimulating alkaline phosphatase (ALP) activity, osteocalcin production, nodule formation, and matrix mineralization. Recent studies reported a role for OA in cell adhesion and integrin binding. In this study, we demonstrate that recombinant osteoactivin (rOA) as a matricellular protein stimulated adhesion, spreading and differentiation of MC3T3-E1 osteoblast-like cells through binding to alphav beta1 integrin and heparan sulfated proteoglycans (HSPGs). MC3T3-E1 cell adhesion to rOA was blocked by neutralizing anti-OA or anti-alphav and beta1 integrin antibodies. rOA stimulated-osteoblast adhesion was also inhibited by soluble heparin and sodium chlorate. Interestingly, rOA stimulated-osteoblast adhesion promoted an increase in FAK and ERK activation, resulting in the formation of focal adhesions, cell spreading and enhanced actin cytoskeleton organization. In addition, differentiation of primary osteoblasts was augmented on rOA coated-wells marked by increased alkaline phosphatase staining and activity. Taken together, these data implicate OA as a matricellular protein that stimulates osteoblast adhesion through binding to alphav beta1 integrin and cell surface HSPGs, resulting in increased cell spreading, actin reorganization, and osteoblast differentiation with emphasis on the positive role of OA in osteogenesis.
Moussa Fouad M; Hisijara Israel Arango; Sondag Gregory R; Scott Ethan M; Frara Nagat; Abdelmagid Samir M; Safadi Fayez F
Journal of cellular biochemistry
2014
2014-07
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1002/jcb.24760" target="_blank" rel="noreferrer noopener">10.1002/jcb.24760</a>